Printing apparatus



Feb; 25,1941. EfWOODDELL 2 2,232,989

I PRINTING APPARATUS V Fil edMay 19., 1935 Ii]. 2. 2 h f INVENTORY GHARLE$ EWOODDELL ATTORNEY. I

of materials having the required properties of toughness, resilience and strong adhesion to paper. One material which I have found to be very satisfactory for this purpose consists of a cellulose ester lacquer such as is readily obtainable under the trade name Duco.

These cellulose ester lacquers commonly consist of a solution of cellulose nitrate together with a suitable plasticizing agent such as dibutyl phthalate which remains in the film of plastic material after the solvents have evaporated and reduces the brittleness of the cellulose nitrate.

The lacquers also commonly contain a resin such as gum dammar, mastic, rosin or shellac. These gums or resins are particularly useful in promoting adhesion of the lacquer coating to the surface being coated as well as for increasing the hardness and otherwise improving the char- I ness, resilience and adhesion to the paper. One

aldehyde or hexamethylenetetramine.

suchresin is the copolymer of vinyl chloride and vinyl acetate obtainable commercially. under the trade name Vinylite. Other vinyl resins are highly polymerized vinyl acetate and the product obtained by hydrolyzing a'vinyl polymer such as polyvinyl acetate with an aldehyde such as acetaldehyde. 7 These latter resins are obtainable under the trade name .Alvarf' Another class of resin which I have found suitable for forming the surface film 9 consists of oil-modified phenolic condensation productsflwhich are obtainable by .reacting a drying oil, for instance tung' oil, with a phenol and subsequently reacting the product so obtained with a methylene body such as form- These products are both heat reactive and oxidizable, and should be applied in the form of solutions of the heat reactive material and-subsequently baked to develop the hardness and toughness ob- ,tainablewhen they are properly cured.

, Still another class of resin which makes a good film for use in my invention comprises the so-called oil-modified alkyd resins. Alkyd resins as a class are the esters obtained byreacting a polyhydric alcohol with a polybasic acid. The so-called oil-modified alkyds are obtained by replacing part of the polybasic acid by the fatty acid of a vegetable oil, preferably a drying oil such as linseed oil or tung oil. These oil-modified resins are both oxidizable and heat reactive and when baked, set up to form hard, tough, adherent films of the character required by my invention. A modification of such resins consists in preparing Ya resincontaining both an oil-modified alkyd resin and a phenolic resin and resins of this class have also been found to be very well suited for use in my invention.

The paper used is preferably a high calendered cylinder paper which is hard, strong and substantially incompressible. Such papers are readily obtainable and are represented by cylinder papers of the type commonly'employed in the manufacture'of sandpaper.

Having prepared a paper with a film of plastic material by using any of the plastic materials above mentioned, the product is then applied to the member which is to support the web or sheet being printed, in the conventional manner.

'Where the sheet is employed as a top sheet for a first impression roll as exemplified by roll 5, Fig. 1, it is not essential that the outer coating 9 be ink repellent but the principal requirements in this application are toughness, resilience and a strong adherence to the paper. Continued pressure of the type carried on the outer surface of roll 3 tends to puncture such materials as ordinary manila paper or paper covered with a sheet of vegetable parchment glued to a sheet of ordinary paper and thus to prevent the clear, sharp printing which is desired. My films of plastic material, 'being extremely tough and resilient, are capable of withstanding the repeated hammering and pressing of the points of the type without becoming distorted or otherwise impaired. When my top sheets are used upon a second impression roll as illustrated by roll I of Fig. 1, it is necessary that they not only be tough, resilient and adherent, for the reasons as described in the-foregoing discussion of roll 5, but they must also be ink'repellent so that they will not pick up ink from the freshly printed surface which passes over them.

' Since these hard pack rolls are very carefully built up and require many hoursof preparation to get them of suitable contour'so that the printing' will be sharp and clean, my improved top sheets have a great advantage in being impenetrable by inkand consequently protecting the under surface of the roll against exposure to ink. If a top sheet is penetrable by ink, the ink.

flat surface and the type and the sheet are pressed together much like'the closing of a book or the sheet is sometimes temporarily secured to the periphery of a cylinder and the freshly inked type is run under the rotating cylinder, the speeds being synchronized so that the impression is transferred to the sheet on the cylinder.

In either kind of printing itfrequently happens that the platen or cylinder which is used to support the sheet which is to be printed is closed up with or passed over the type without a fresh sheet having been inserted. In such a case the press will, of course, make an impression on the draw sheet covering the outer surface of the platen or cylinder which will offset from the draw sheet onto the freshly printed sheet being carried by this impression cylinder. It usually requires about ten sheets to completely remove the, ink

comprisin a vinyl resin.

It will thusbe seen that in providing a. printing accessory in the form of a top sheet consisting of a sheet of hard, 1inyielding, substantially incompressible paper coated with a film of plastic material which is tough, resilient, strongly ad- 1. A printing accessory forsupporting a sheet to be printed consisting of a sheet of hard and substantially unyielding paper adhesivelyfcoated with a tough resilient film of plastic material comprising a synthetic resin.

2. A printing accessory for supporting a sheet to, be printed consisting of a sheet of hard and substantially unyielding paper adhesively coated with a tough resilient film of 3. A printing accessory for supporting a sheet to be printed consisting of a sheet of hard and substantially unyielding paper adhesively coated with a tough resilient film of plasticmaterial plastic material comprising a hardened oil-modified synthetic resin.

4. A printing accessory for supporting a sheet to be printed consisting of a sheet of hard and substantially unyielding paper adhesively coated Hwith a tough resilient film of plastic material comprising polyvinyl acetate hydrolyzed, by reaction with an aldehyde. f

5. A printing accessory for supporting a sheet to beprinted consistingof a sheet of hard and subnantially unyielding paper adhesively coated with a tough resilient film of plastic material comprising a cellulose ester and a resin.

6. A printing accessory for supporting a sheet to beprinted consisting of a sheet of hard and substantially unyieldingpaper adhesively coated with a toughiresilient film of plastic material comprising cellulose nitrate and a resin. 7. A printing accessory for supporting a sheet to be printed consisting or a sheet of hard, strong,

substantially unyielding paper having adhering thereto a tough resilient film of plastic material comprising a cellulose ester, a resin and a plasticizer. e

8. A printing accessory for supporting a sheet to be printed consisting of a sheet of hard, strong,

substantially unyielding paper having adhering thereto a tough resilient film of a plastic material comprising cellulose nitrate, a plasticizing agent and a resin.-

CHARLES E. WOODDELL. 

